Radio frequency ic device

ABSTRACT

A radio frequency IC device includes a radio frequency IC chip, a feeder circuit substrate, and a radiating plate. The feeder circuit substrate includes a feeder circuit that electrically connects to the radio IC chip and that includes a resonance circuit and/or a matching circuit including inductance elements. The feeder circuit substrate is bonded to the radiating plate, which radiates a transmission signal supplied from the feeder circuit and supplies a received signal to the feeder circuit. The inductance elements are arranged in spiral patterns wound in opposite directions and couple to each other in opposite phases. The radio frequency IC device is able to obtain a radio frequency IC device that is not susceptible to being affected by a usage environment, minimizes variations in radiation characteristics, and can be used in a wide frequency band.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radio frequency IC (integratedcircuit) device. More particularly, the present invention relates to aradio frequency IC device used in a RFID (radio frequencyidentification) system.

2. Description of the Related Art

Previous RFID systems have been developed as a system to managearticles. In this RFID system, a reader/writer generating an inductionfield and a radio frequency tag (also called a radio frequency ICdevice) that is attached to an article and that stores predeterminedinformation communicate with each other in a non-contact manner totransmit information. As a radio frequency tag used in this type of RFIDsystem, Japanese Unexamined Patent Application Publication No.2006-80367 suggests a radio frequency tag including an antenna and amatching circuit placed on a flexible substrate and an IC chipelectrically continuous to the antenna and the matching circuit. In thistag, the matching circuit is constituted by forming a loop coil(inductor) on the substrate.

However, in the radio frequency tag described in Japanese UnexaminedPatent Application Publication No. 2006-80367, the matching circuit toperform impedance matching between the IC chip and the antenna isexposed on the flexible substrate. This configuration has a disadvantageof causing variations in inductance of the loop coil and incharacteristics of the matching circuit depending on the permittivity ofthe article to which the radio frequency tag is attached or thecircumstances of the article. These variations cause transmission lossof signals between the IC chip and the antenna, resulting indisadvantageous degradation of radiation characteristics of the antenna.On the other hand, the usable frequency of the radio frequency tag isdetermined depending on the length of the antenna. The antenna needs tobe designed in accordance with the permittivity and othercharacteristics of the article to which the antenna is to be attached,which is very inconvenient.

SUMMARY OF THE INVENTION

In order to overcome the problems described above, preferred embodimentsof the present invention provide a radio frequency IC device that is notsusceptible to being affected by a usage environment, that can preventvariations in radiation characteristics, and that can be used in a widefrequency band.

A radio frequency device according to a preferred embodiment of thepresent invention includes a radio frequency IC chip, a feeder circuitsubstrate electrically connected to the radio frequency IC chip andprovided with a feeder circuit including a resonance circuit and/or amatching circuit including at least two inductance elements, and aradiating plate to radiate a transmission signal supplied from thefeeder circuit and/or supply a received signal to the feeder circuit,the feeder circuit substrate being bonded to or placed near theradiating plate. The at least two inductance elements are arranged inspiral patterns wound in opposite directions.

In the radio frequency IC device according to a preferred embodiment ofthe present invention, a resonance frequency of a signal is set in thefeeder circuit provided in the feeder circuit substrate. Thus, the radiofrequency IC device normally operates when being attached to variousarticles, variations in radiation characteristic are prevented, andthere is no need to change the design of the radiating plate forindividual articles. Particularly, the at least two inductance elementsprovided in the feeder circuit substrate are wound in oppositedirections, and thus magnetic fields generated by the inductanceelements are canceled out, a Q value becomes small with no steepness inresonance characteristic, and thus a wideband characteristic can beobtained near the resonance frequency. Also, the directions of themagnetic fields are opposite of one another. That is, when one of themagnetic fields is directed upward, the other is directed downward. Thiscorresponds to positive and negative of an AC supply, enabling almost100% energy transmission to the radiating plate via magnetic fieldenergy.

The frequency of a transmission signal radiated from the radiating plateand the frequency of a reception signal supplied to the radio frequencyIC chip substantially correspond to the resonance frequency of theresonance circuit in the feeder circuit substrate. A maximum gain of thesignals is substantially determined by at least one of the size andshape of the feeder circuit and the distance and medium between thefeeder circuit and the radiating plate. Since the frequencies of thetransmission/reception signals are determined in the feeder circuitsubstrate, a stable frequency characteristic can be obtained whilepreventing a change in the frequency characteristic in any shape or sizeof the radiating plate and a positional relationship, for example, evenif the radio frequency IC device is rolled or is sandwiched bydielectrics.

In a radio frequency IC device according to a preferred embodiment ofthe present invention, the at least two inductance elements may beplaced in different positions when the feeder circuit substrate isviewed in a perspective plan view. The feeder circuit can be coupled totwo different radiating plates.

Each of the at least two inductance elements may preferably be definedby two wiring electrodes adjacent to each other on the same plane. Whenone inductance element is constituted by two adjacent wiring electrodes,a wideband resonance characteristic can be obtained by changing thelength of the wiring electrodes or the gap therebetween.

The feeder circuit substrate may include a laminate and the inside orsurface of a bottom layer of the laminate may be provided with flatelectrodes, the size thereof being the about the same as, or smallerthan that of an outer shape of the at least two inductance elements whenthe feeder circuit substrate is viewed in a perspective plan view. Byproviding the flat electrodes, variations in coupling between the feedercircuit and the radiating plate can be minimized.

The feeder circuit substrate may preferably include a magnetic substanceand the at least two inductance elements may be placed in the magneticsubstance. By providing the magnetic substance in the feeder circuitsubstrate, a large inductance value can be obtained to deal with afrequency of an approximately 13.56 MHz band, for example.

The radiating plate may be defined by a loop-shaped electrode two endsthat may couple to one of the at least two inductance elements. Also, amagnetic substance may be placed inside or on a surface of a loop of theloop-shaped electrode. With this configuration, a magnetic fieldgenerated by the radiating plate including the loop-shaped electrode isamplified and the transmission distance increases.

The at least two inductance elements may connect to the radio frequencyIC chip in series or in parallel. Also, inductance values of the atleast two inductance elements may be the same or substantially the same.

A plurality of mount electrodes arranged to mount the radio frequency ICchip may be located on a principal surface of the feeder circuitsubstrate and at least two of the plurality of mount electrodes may beelectrically in conduction via the feeder circuit. The at least twomount electrodes may be balanced input/output terminal electrodes. Thefeeder circuit may include an auxiliary matching circuit whose one endelectrically connects to a predetermined position of the feeder circuitand whose other end is electrically open. The auxiliary matching circuitenables a matching state to be finely adjusted. Also, the at least twomount electrodes may be balanced input/output terminal electrodes.

A portion of the at least two inductance elements may be exposed on aside surface of the feeder circuit substrate and the exposed portion mayfunction also as a radiating plate. The portion of the inductanceelements electromagnetically couples to the radiating plate on the sidesurface of the feeder circuit substrate, so that the radiationcharacteristic is enhanced.

The feeder circuit substrate may be a multilayer substrate made of, forexample, ceramic or resin, or may be a flexible substrate. Particularly,by providing the inductance elements constituting the feeder circuit inthe substrate, the feeder circuit is not susceptible to being affectedby the outside of the substrate, so that variations in radiationcharacteristic can be prevented.

According to a preferred embodiment of the present invention, a feedercircuit substrate including a resonance circuit and/or a matchingcircuit is provided between a radio frequency IC chip and a radiatingplate. With this configuration, the resonance frequency and theradiation characteristic of a radio frequency IC device are effectivelynot susceptible to being affected by an article to which the radiofrequency IC device is attached. Furthermore, since at least twoinductance elements provided in the feeder circuit substrate arespirally wound in opposite directions, magnetic fields generated therebyare canceled out and a wideband characteristic can be obtained near theresonance frequency.

These and other features, elements, arrangements, steps, characteristicsand advantages of the present invention will become more apparent fromthe following detailed description of preferred embodiments of thepresent invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram illustrating a feeder circuit ofa radio frequency IC device according to a first preferred embodiment ofthe present invention.

FIGS. 2A and 2B illustrate a radiating substrate constituting the radiofrequency IC device according to the first preferred embodiment, whereinFIG. 2A is a plan view and FIG. 2B is a plan view illustrating a statein which a feeder circuit substrate is bonded.

FIG. 3 is a perspective view illustrating a state where a radiofrequency IC chip is mounted on the feeder circuit substrateconstituting the radio frequency IC device according to the firstpreferred embodiment of the present invention.

FIG. 4 is a plan view illustrating a lamination structure of the feedercircuit substrate of the radio frequency IC device according to thefirst preferred embodiment of the present invention.

FIG. 5 is a plan view illustrating a lamination structure of a feedercircuit substrate of a radio frequency IC device according to a secondpreferred embodiment of the present invention.

FIG. 6 is an equivalent circuit diagram of a radio frequency IC deviceaccording to a third preferred embodiment of the present invention.

FIGS. 7A-7C illustrate a radiating substrate of the radio frequency ICdevice according to the third preferred embodiment, wherein FIG. 7A is aplan view, FIG. 7B is a back view, and FIG. 7C is a plan view of amagnetic substance provided on the rear surface.

FIG. 8 is a plan view illustrating a lamination structure of a feedercircuit substrate of the radio frequency IC device according to thethird preferred embodiment of the present invention.

FIG. 9 is a perspective view illustrating a radio frequency IC deviceaccording to a fourth preferred embodiment of the present invention.

FIG. 10 is a plan view illustrating a lamination structure of a feedercircuit substrate of the radio frequency IC device according to thefourth preferred embodiment of the present invention.

FIG. 11 is a plan view illustrating a lamination structure of a feedercircuit substrate of a radio frequency IC device according to a fifthpreferred embodiment of the present invention.

FIG. 12 is a perspective view illustrating a lamination structure of afeeder circuit substrate of a radio frequency IC device according to asixth preferred embodiment of the present invention.

FIG. 13 is a perspective view illustrating a lamination structure of afeeder circuit substrate of a radio frequency IC device according to aseventh preferred embodiment of the present invention.

FIG. 14 is a perspective view illustrating a lamination structure of afeeder circuit substrate of a radio frequency IC device according to aneighth preferred embodiment of the present invention.

FIG. 15 is an equivalent circuit diagram of the feeder circuit substrateillustrated in FIG. 14.

FIG. 16 is a perspective view illustrating another lamination structureof the feeder circuit substrate of the radio frequency IC deviceaccording to the eighth preferred embodiment of the present invention.

FIG. 17 is an equivalent circuit diagram of the feeder circuit substrateillustrated in FIG. 16.

FIG. 18 is a perspective view illustrating a radio frequency IC deviceaccording to a ninth preferred embodiment of the present invention.

FIG. 19 is a perspective view showing a can including the radiofrequency IC device according to the tenth preferred embodiment of thepresent invention.

FIG. 20 is a cut-away view showing a can including the radio frequencyIC device according to the tenth preferred embodiment of the presentinvention.

FIG. 21 is an equivalent circuit diagram of the feeder circuit substrateaccording to a tenth preferred embodiment of the present invention.

FIGS. 22A-22G are cut-away views showing a manufacturing process of acircuit substrate according to the tenth preferred embodiment of thepresent invention.

FIGS. 23A and 23B are plan views showing a layout of a radio frequencyIC device according to the tenth preferred embodiment of the presentinvention.

FIG. 24 is an equivalent circuit diagram of the feeder circuit substrateaccording to an eleventh preferred embodiment of the present invention.

FIGS. 25A-25G are cut-away views showing a manufacturing process of acircuit substrate according to the eleventh preferred embodiment of thepresent invention.

FIG. 26A-26C are plan views showing a layout of a radio frequency ICdevice according to the eleventh preferred embodiment of the presentinvention.

FIGS. 27A and 27B are equivalent circuit diagrams of the feeder circuitsubstrate according to a twelfth preferred embodiment and a thirteenthpreferred embodiment of the present invention, respectively.

FIGS. 28A and 28B are equivalent circuit diagrams of the feeder circuitsubstrate according to a fourteenth preferred embodiment and a fifteenthpreferred embodiment of the present invention, respectively.

FIGS. 29A-29D are cut-away and plan views of a configuration of thetwelfth to fifteenth preferred embodiments of the present invention.

FIG. 30 is a perspective view illustrating a lamination structure of afeeder circuit substrate of a radio frequency IC device according totwelfth to fifteenth preferred embodiments of the present invention.

FIGS. 31A-31D are plan views showing a radiating substrate according tothe twelfth to fifteenth preferred embodiments of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the radio frequency IC deviceaccording to the present invention are described with reference to theattached drawings.

First Preferred Embodiment FIGS. 1 to 4

A radio frequency IC device according to a first preferred embodimentincludes a radio frequency IC chip 10 arranged to processtransmission/reception signals of predetermined frequencies and a feedercircuit substrate 20 on which the radio frequency IC chip 10 is mountedillustrated in FIG. 3, and also includes a radiating substrate 30illustrated in FIG. 2A or FIG. 2B.

As illustrated in an equivalent circuit diagram in FIG. 1, the feedercircuit substrate 20 includes a feeder circuit 21 (the details aredescribed below with reference to FIG. 4) having a resonance circuit anda matching circuit including inductance elements L1 and L2, which haveinductance values that are different from each other and whichmagnetically couple to each other in opposite phases (indicated bymutual inductance M).

The radio frequency IC chip 10 includes, for example, a clock circuit, alogic circuit, a memory circuit, and so on, stores necessaryinformation, and is provided with a pair of input/output terminalelectrodes and a pair of mounting terminal electrodes on its rearsurface (not illustrated). As illustrated in FIG. 3, the input/outputterminal electrodes electrically connect to feeder terminal electrodes42 a and 42 b arranged on the feeder circuit substrate 20, and themounting terminal electrodes electrically connect to mount electrodes 43a and 43 b, through metal bumps or the like.

As illustrated in FIGS. 2A and 2B, in the radiating substrate 30, aloop-shaped radiating plate 32 preferably made of a non-magneticmetallic material is placed on a flexible resin film substrate 31 alongthe edge thereof. The feeder circuit substrate 20 is bonded to endportions 32 a and 32 b by an adhesive. Each of the end portions 32 a and32 b couples to any of the inductance elements L1 and L2 of the feedercircuit 21. Also, a magnetic substance 33 is placed inside the loop ofthe radiating plate 32. FIG. 2B illustrates a state where the feedercircuit substrate 20 on which the radio frequency IC chip 10 is mountedis bonded to the radiating plate 32 of the radiating substrate 30.

The inductance elements L1 and L2 included in the feeder circuit 21magnetically couple to each other in opposite phases, resonate withfrequencies processed by the radio frequency IC chip 10, and alsoelectromagnetically couple to the end portions 32 a and 32 b of theradiating plate 32. The feeder circuit 21 realizes matching between theimpedance of the radio frequency IC chip 10 (normally about 50Ω) and theimpedance of the radiating plate 32 (spatial impedance of about 377Ω).

Therefore, the feeder circuit 21 transmits a transmission signal thathas a predetermined frequency and that is output from the radiofrequency IC chip 10 to the radiating plate 32, selects a signalcomponent having a predetermined frequency from a signal received fromthe radiating plate 32, and supplies the selected signal component tothe radio frequency IC chip 10. Accordingly, in this radio frequency ICdevice, the radio frequency IC chip 10 operates in accordance with asignal received by the radiating plate 32 and a response signal from theradio frequency IC chip 10 is externally radiated from the radiatingplate 32.

As described above, in this radio frequency IC device, the resonancefrequency of signals is set in the feeder circuit 21 provided in thefeeder circuit substrate 20. Thus, the radio frequency IC devicenormally operates when being attached to various articles, variations inradiation characteristic can be prevented, and there is no need todesign the radiating plate 32 and so on for individual articles. Thefrequency of a transmission signal radiated from the radiating plate 32and the frequency of a reception signal supplied to the radio frequencyIC chip 10 substantially correspond to the resonance frequency of thefeeder circuit 21 in the feeder circuit substrate 20. A maximum gain ofthe signals is substantially determined by at least one of the size andshape of the feeder circuit 21 and the distance and medium between thefeeder circuit and the radiating plate. Since the frequencies oftransmission/reception signals are determined in the feeder circuitsubstrate 20, a stable frequency characteristic can be obtained whilepreventing a change in the frequency characteristic in any shape or sizeof the radiating plate 32 and a positional relationship, for example,even if the radio frequency IC device is rolled or is sandwiched bydielectrics.

Now, a configuration of the feeder circuit substrate 20 is describedwith reference to FIG. 4. The feeder circuit substrate 20 is formed by,for example, laminating, crimping, and firing ceramic sheets 41 a to 41h made of a dielectric or magnetic material. The sheet 41 a in the toplayer is provided with the feeder terminal electrodes 42 a and 42 b, themount electrodes 43 a and 43 b, and via-hole conductors 44 a, 44 b, 45a, and 45 b. Each of the sheets 41 b to 41 h in the second to eighthlayers is provided with wiring electrodes 46 a and 46 b defining theinductance elements L1 and L2, and is also provided with via-holeconductors 47 a, 47 b, 48 a, and 48 b as necessary.

By laminating the sheets 41 a to 41 h, the wiring electrodes 46 a arespirally connected via the via-hole conductors 47 a to form theinductance element L1, while the wiring electrodes 46 b are spirallyconnected via the via-hole conductors 47 b to form the inductanceelement L2. Also, a capacitance is formed between lines of the wiringelectrodes 46 a and 46 b.

An end portion 46 a-1 of the wiring electrode 46 a on the sheet 41 bconnects to the feeder terminal electrode 42 a via the via-holeconductor 45 a, and an end portion 46 a-2 of the wiring electrode 46 aon the sheet 41 h connects to the feeder terminal electrode 42 b via thevia-hole conductors 48 a and 45 b. An end portion 46 b-1 of the wiringelectrode 46 a on the sheet 41 b connects to the feeder terminalelectrode 42 b through the via-hole conductor 44 b, and an end portion46 b-2 of the wiring electrode 46 b on the sheet 41 h connects to thefeeder terminal electrode 42 a via the via-hole conductors 48 b and 44a.

In the above-described feeder circuit 21, the inductance elements L1 andL2 are wound in the directions opposite to each other, and thus magneticfields generated by the inductance elements L1 and L2 are canceled out.Because the magnetic fields are canceled out, the wiring electrodes 46 aand 46 b need to be long to some extent in order to obtain a desiredinductance value. This causes a Q value to be small with no steepness inresonance characteristic, and thus a wideband characteristic can beobtained near the resonance frequency.

The inductance elements L1 and L2 are placed in different positions onthe right and left when the feeder circuit substrate 20 is viewed in aperspective plan view. The directions of the magnetic fields generatedby the inductance elements L1 and L2 are opposite to each other.Accordingly, when the feeder circuit 21 is coupled to the end portions32 a and 32 b of the loop-shaped radiating plate 32, currents areexcited in opposite directions in the end portions 32 a and 32 b, sothat signals can be transmitted/received by the loop-shaped radiatingplate 32. Alternatively, the inductance elements L1 and L2 may becoupled to two different radiating plates, respectively.

The radiating plate 32 is defined by a loop-shaped electrode having theend portions 32 a and 32 b, which couple to the inductance elements L1and L2, respectively. The magnetic substance 33 made of ferrite or thelike is placed inside the loop-shaped electrode. The magnetic substance33 causes the magnetic field generated by the radiating plate 32including the loop-shaped electrode to be amplified, so that acommunication distance increases. The magnetic substance 33 is notalways necessary, and can be omitted.

By using a magnetic material in the feeder circuit substrate 20 andproviding the inductance elements L1 and L2 in the magnetic substance, alarge inductance value can be obtained to deal with a frequency of anapproximately 13.56 MHz band, for example. Furthermore, even ifprocessing, variations of a magnetic sheet or variations in permeabilityoccur, variations in impedance with respect to that of the radiofrequency IC chip 10 can be absorbed. The permeability μ of the magneticsubstance is preferably about 400, for example.

By setting the inductance values of the two inductance elements L1 andL2 to the same or substantially the same values, the intensities ofmagnetic fields generated by the inductance elements L1 and L2 can bemade equal to each other. Accordingly, the canceling amounts of themagnetic fields in the two inductance elements L1 and L2 can be madeequal to each other, so that a wideband characteristic near theresonance frequency can be obtained.

The feeder circuit substrate 20 may be a multilayer substrate made of,for example, ceramic or resin, or may be a substrate including, forexample, a laminate of flexible sheets made of a dielectric material,such as polyimide or liquid crystal polymer. Particularly, theconfiguration in which the inductance elements L1 and L2 are integratedin the feeder circuit substrate 20 enables the feeder circuit 21 to benot susceptible to being affected by the outside of the substrate, sothat variations in radiation characteristic can be prevented.

The feeder circuit substrate 20 need not be bonded to the end portions32 a and 32 b of the radiating plate 32, and may be placed near the endportions 32 a and 32 b.

Second Preferred Embodiment FIG. 5

A radio frequency IC device according to a second preferred embodimentpreferably has basically the same configuration as that of the firstpreferred embodiment. As illustrated in FIG. 5, the difference betweenthe first and second preferred embodiments is that flat electrodes 49 aand 49 b are provided on the rear surface of a sheet 41 i in the bottomlayer of the feeder circuit substrate 20. The size of the flatelectrodes 49 a and 49 b preferably is the approximately the same as orsmaller than that of the outer shape of the inductance elements L1 andL2, when the feeder circuit substrate 20 is viewed in a perspective planview.

Via-hole conductors are placed at the end portions 46 a-2 and 46 b-2 ofthe wiring electrodes 46 a and 46 b forming the inductance elements L1and L2. Those via-hole conductors connect to the feeder terminalelectrodes 42 a and 42 b and also connect to the flat electrodes 49 aand 49 b via via-hole conductors 48 c and 48 d provided on the sheet 41i. By providing the flat electrodes 49 a and 49 b, variations incoupling between the feeder circuit 21 and the radiating plate 32 can beminimized.

The flat electrodes 49 a and 49 b need not be electrically connected tothe wiring electrodes 46 a and 46 b, and may be electrically connectedto the radiating plate 32.

Third Preferred Embodiment FIGS. 6 to 8

In a radio frequency IC device according to a third preferredembodiment, as illustrated in FIG. 7A, the feeder circuit substrate 20on which the radio frequency IC chip 10 is mounted is bonded to an endportion 53 b of an electrode 53 and an electrode 54 placed on a frontsurface of a radiating substrate 50 by an adhesive. The radio frequencyIC chip 10 preferably has substantially the same configuration as thatof the first preferred embodiment.

In the radiating substrate 50, the spiral electrode 53 and the electrode54 defining a radiating plate 52 are placed on the front surface of aflexible resin film substrate 51, as illustrated in FIG. 7A, and aspiral electrode 55 defining the radiating plate 52 is placed on therear surface thereof, as illustrated in FIG. 7B.

An end portion 53 a of the electrode 53 electrically connects to an endportion 55 a of the electrode 55 via a via-hole conductor 56 a, and anend portion 55 b of the electrode 55 electrically connects to theelectrode 54 via a via-hole conductor 56 b. On the rear surface of thesubstrate 50, a magnetic substance 57 made of ferrite or the like isplaced on the electrode 55 inside the outer edge of the electrode 55.The magnetic substance 57 may be made of a magnetic metal material. Inthat case, the magnetic substance 57 needs to be electrically insulatedfrom the electrode 55.

In the feeder circuit substrate 20, as illustrated in an equivalentcircuit diagram in FIG. 6, the inductance elements L1 and L2 andinductance elements L3 and L4 having inductance values different fromeach other magnetically couple to each other in the same phase,respectively (mutual inductance M1), and the inductance elements L1 andL2 magnetically couple to the inductance elements L3 and L4 in oppositephases (mutual inductance M2). The feeder circuit 21 including aresonance circuit and a matching circuit including the inductanceelements L1, L2, L3, and L4 is described below with reference to FIG. 8.

The inductance elements L1 and L2 and inductance elements L3 and L4included in the feeder circuit 21 magnetically couple to each other inopposite phases to resonate with frequencies processed by the radiofrequency IC chip 10, and also electromagnetically couple to the endportion 53 b and the electrode 54 of the loop-shaped radiating plate 52.Feeder terminal electrodes 62 a and 62 b of the feeder circuit 21electrically connect to input/output terminal electrodes (notillustrated) of the radio frequency IC chip 10 so as to realize matchingbetween the impedance of the radio frequency IC chip 10 (normally about50Ω) and the impedance of the radiating plate 52 (spatial impedance ofabout 377Ω).

In the third preferred embodiment, if a signal of a positive polarity isapplied to the electrode 54 of the loop-shaped radiating plate 52, asignal of a negative polarity is applied to the end portion 53 b.Accordingly, a current flows from a positive (electrode 54) to anegative (end portion 53 b) direction, so that a signal is transmittedbetween the radiating plate 52 and the feeder circuit 21.

Therefore, as in the first preferred embodiment, the feeder circuit 21transmits a transmission signal that is output from the radio frequencyIC chip 10 and that has a predetermined frequency to the radiating plate52, and also selects a reception signal having a predetermined frequencyfrom a signal received by the radiating plate 52 and supplies theselected signal to the radio frequency IC chip 10. Accordingly, in thisradio frequency IC device, the radio frequency IC chip 10 is operated bya signal received by the radiating plate 52 and a response signal fromthe radio frequency IC chip 10 is externally radiated from the radiatingplate 52. As described above, the operation and effect of the thirdpreferred embodiment are basically the same as those of the firstpreferred embodiment.

Now, a configuration of the feeder circuit substrate 20 is describedwith reference to FIG. 8. The feeder circuit substrate 20 is formed by,for example, laminating, crimping, and firing ceramic sheets 61 a to 61h preferably made of a dielectric or magnetic material. The sheet 61 ain the top layer is provided with the feeder terminal electrodes 62 aand 62 b, mount electrodes 63 a and 63 b, and via-hole conductors 64 a,64 b, 65 a, and 65 b. Each of the sheets 61 b to 61 h in the second toeighth layers is provided with wiring electrodes 66 a, 66 b, 66 c, and66 d defining the inductance elements L1, L2, L3, and L4 and is alsoprovided with via-hole conductors 67 a, 67 b, 67 c, 67 d, 68 a, and 68 bas necessary.

By laminating the sheets 61 a to 61 h, the wiring electrodes 66 a arespirally connected via the via-hole conductors 67 a to form theinductance element L1, while the wiring electrodes 66 b are spirallyconnected via the via-hole conductors 67 b to form the inductanceelement L2. Also, the wiring electrodes 66 c are spirally connected viathe via-hole conductors 67 c to form the inductance element L3, whilethe wiring electrodes 66 d are spirally connected via the via-holeconductors 67 d to form the inductance element L4. Also, a capacitanceis formed between lines of the wiring electrodes 66 a, 66 b, 66 c, and66 d.

An end portion 66-1 where the wiring electrodes 66 a and 66 b on thesheet 61 b are integrated connects to the feeder terminal electrode 62 avia the via-hole conductor 65 a, and an end portion 66-2 where thewiring electrodes 66 a and 66 b on the sheet 41 h are integratedconnects to the feeder terminal electrode 62 b via the via-holeconductors 68 a and 65 b. An end portion 66-3 where the wiringelectrodes 66 c and 66 d on the sheet 61 b are integrated connects tothe feeder terminal electrode 62 b via the via-hole conductor 64 b, andan end portion 66-4 where the wiring electrodes 66 c and 66 d on thesheet 61 h are integrated connects to the feeder terminal electrode 62 avia the via-hole conductors 68 b and 64 a.

The operation of the feeder circuit 21 having the above-describedconfiguration is basically the same as that of the feeder circuit 21described above in the first preferred embodiment. Particularly, theinductance elements L1 and L2 and the inductance elements L3 and L4 aredefined by the two wiring electrodes 66 a and 66 b and the two wiringelectrodes 66 c and 66 d that are adjacent to each other on the sameplane. With this configuration, a wideband resonance characteristic canbe obtained by changing the length of the wiring electrodes or the gapbetween the electrodes.

The radiating plate 52 is constituted by the loop-shaped electrodeincluding the end electrode 53 a on one side and the end electrode 54 onthe other side, and the end electrodes 53 a and 54 couple to thedifferent inductance elements L1 and L2 and L3 and L4, respectively.Furthermore, since the magnetic substance 57 is placed inside the outeredge of the loop-shaped electrode, the magnetic field generated by theradiating plate 52 including the loop-shaped electrode is amplified andthe communication distance increases. The magnetic substance 57 is notalways necessary and can be omitted.

Fourth Preferred Embodiment FIGS. 9 and 10

As illustrated in FIG. 9, a radio frequency IC device according to afourth preferred embodiment includes the radio frequency IC chip 10, thefeeder circuit substrate 20, and a radiating substrate 130 including aradiating plate 132.

The radio frequency IC chip 10 preferably has the same configuration asthat of the first preferred embodiment. The feeder circuit substrate 20includes two inductance elements L1 and L2. Feeder terminal electrodes72 a and 72 b and mount electrodes 73 a and 73 b placed on a frontsurface of the feeder circuit substrate 20 electrically connect toinput/output terminal electrodes and mounting terminal electrodes (notillustrated) of the radio frequency IC chip 10.

In the radiating substrate 130, the spiral radiating plate 132 is placedin a half portion of the front surface of a ceramic substrate 131 and aspiral auxiliary electrode 133 is placed in the other half portion. Thefeeder circuit substrate 20 on which the radio frequency IC chip 10 ismounted is bonded to the radiating plate 132 preferably by an adhesive,for example. Also, in the auxiliary electrode 133, an end portion 133 apositioned at the center connects to an electrode 135 placed on the rearsurface of the substrate 131 via a via-hole conductor 134, and an endportion 135 a of the electrode 135 capacitively couples to an endportion 132 a positioned at the center of the radiating plate 132.Alternatively, the electrode 135 may be placed inside the substrate 131.

As illustrated in FIG. 10, the feeder circuit substrate 20 is formed by,for example, laminating, crimping, and firing ceramic sheets 71 a to 71e made of, for example, a dielectric or magnetic material. The sheet 71a in the top layer is provided with the feeder terminal electrodes 72 aand 72 b, the mount electrodes 73 a and 73 b, and via-hole conductors 74a and 74 b. Each of the sheets 71 b to 71 d in the second to fourthlayers is provided with wiring electrodes 75 a and 75 b defining theinductance elements L1 and L2 and via-hole conductors 76 a, 76 b, and77. The sheet 71 e in the bottom layer is provided with a wiringelectrode 75. The wiring electrodes 75 a and 75 are exposed at theperiphery of the respective sheets 71 b to 71 e.

By laminating the sheets 71 a to 71 e, the wiring electrodes 75 a arespirally connected via the via-hole conductors 76 a to form theinductance element L1, while the wiring electrodes 75 b are spirallyconnected via the via-hole conductors 76 b to form the inductanceelement L2. The wiring electrodes 75 a and 75 b branch on the sheet 71 band are integrated in the wiring electrode 75 on the sheet 71 e in thebottom layer. Also, a capacitance is formed between lines of the wiringelectrodes 75 a and 75 b.

An end portion 75 c where the wiring electrodes 75 a and 75 b on thesheet 71 b are integrated connects to the feeder terminal electrode 72 bvia the via-hole conductor 74 b, an end portion 75 d of the wiringelectrode 75 on the sheet 71 e connects to the wiring electrodes 75 aand 75 b via the via-hole conductors 76 a and 76 b on the next uppersheet 71 d. Also, an end portion 75 e of the wiring electrode 75connects to the feeder terminal electrode 72 a via the via-holeconductors 77 and 74 a.

The feeder circuit 21 having the above-described configuration includingthe inductance elements L1 and L2 has the same equivalent circuit asthat of the feeder circuit 21 illustrated in FIG. 1. The inductanceelements L1 and L2 magnetically couple to each other in opposite phasesand resonate with frequencies processed by the radio frequency IC chip10, and also electromagnetically couple to the radiating plate 132.Also, the feeder circuit 21 realizes matching between the impedance ofthe radio frequency IC chip 10 (normally about 50Ω) and the impedance ofthe radiating plate 132 (spatial impedance of about 377Ω).

Thus, the operation and effect of the fourth preferred embodiment arethe same as those of the first preferred embodiment. Particularly, inthe fourth preferred embodiment, a portion of the inductance elements L1and L2 (the wiring electrodes 75 a and 75) is exposed on a side surfaceof the feeder circuit substrate 20, and this exposed portion alsofunctions as a radiating plate. Furthermore, the exposed portion of theinductance elements L1 and L2 electromagnetically couples to theradiating plate 132 and the auxiliary electrode 133 on the side surfaceof the feeder circuit substrate 20, so that the radiating characteristicis enhanced. The outer dimension of the auxiliary electrode 133 is thesame as or larger than the outer dimension of the feeder circuitsubstrate 20, and thus the auxiliary electrode 133 can easily couple tothe magnetic field radiated from the rear and side surfaces of thefeeder circuit substrate 20.

Fifth Preferred Embodiment FIG. 11

A radio frequency IC device according to a fifth preferred embodimentincludes the feeder circuit substrate 20 illustrated in FIG. 11. Theother components, that is, the radio frequency IC chip 10 and theradiating substrate 30, are preferably the same as those of the firstpreferred embodiment.

The feeder circuit substrate 20 is formed by, for example, laminating,crimping, and firing ceramic sheets 81 a to 81 e made of, for example, adielectric or magnetic material. The sheet 81 a in the top layer isprovided with feeder terminal electrodes 82 a and 82 b, mount electrodes83 a and 83 b, and via-hole conductors 84 a and 84 b. The sheet 81 b inthe second layer is provided with a wiring electrode 85 and via-holeconductors 86 a, 86 b, 87 a, and 87 b. The sheet 81 c in the third layeris provided with wiring electrodes 85 a and 85 b defining the inductanceelements L1 and L2 and via-hole conductors 86 a, 86 b, 87 a, and 87 b.The sheet 81 d in the fourth layer is provided with wiring electrodes 85a and 85 b constituting the inductance elements L1 and L2. The rearsurface of the sheet 81 e in the bottom layer is provided with flatelectrodes 88 a and 88 b.

By laminating the sheets 81 a to 81 e, the wiring electrodes 85 a arespirally connected via the via-hole conductors 86 a to form theinductance element L1, while the wiring electrodes 85 b are spirallyconnected via the via-hole conductors 86 b to form the inductanceelement L2. Also, a capacitance is provided between lines of the wiringelectrodes 85 a and 85 b.

The wiring electrodes 85 a and 85 b are integrated in the wiringelectrode 85 on the sheet 81 b, an end portion 85 a′ of the wiringelectrode 85 a on the sheet 81 d connects to the feeder terminalelectrode 82 a via the via-hole conductors 87 a and 84 a, and an endportion 85 b′ of the wiring electrode 85 b connects to the feederterminal electrode 82 b via the via-hole conductors 87 b and 84 b.

The feeder circuit 21 having the above-described configuration includingthe inductance elements L1 and L2 has the same equivalent circuit asthat of the feeder circuit 21 illustrated in FIG. 1. The inductanceelements L1 and L2 magnetically couple to each other in opposite phasesand resonate with frequencies processed by the radio frequency IC chip10, and also electromagnetically couple to the radiating plate 32. Also,the feeder circuit 21 realizes matching between the impedance of theradio frequency IC chip 10 (normally about 50Ω) and the impedance of theradiating plate 32 (spatial impedance of about 377Ω).

Thus, the operation and effect of the fifth preferred embodiment are thesame as those of the first preferred embodiment. Particularly, byproviding the flat electrodes 88 a and 88 b on the rear surface of thefeeder circuit substrate 20, variations in coupling between the feedercircuit 21 and the radiating plate 32 can be minimized. However, theflat electrodes 88 a and 88 b are not always necessary, and can beomitted if so desired.

Sixth Preferred Embodiment FIG. 12

A radio frequency IC device according to a sixth preferred embodimentincludes the feeder circuit substrate 20 illustrated in FIG. 12. Theother components, that is, the radio frequency IC chip 10 and theradiating substrate 30, are preferably the same as those of the firstpreferred embodiment.

The configuration of the feeder circuit substrate 20 preferably isbasically the same as that of the feeder circuit substrate 20 accordingto the first preferred embodiment. That is, spirally connected wiringelectrodes 101 a and 101 b define the inductance elements L1 and L2. Theinductance elements L1 and L2 have inductance values different from eachother and magnetically couple to each other in opposite phases.

Furthermore, flat electrodes 102 a and 102 b are disposed immediatelybelow the inductance elements L1 and L2, and spirally connected wiringelectrodes 103 define a magnetic field receiving coil 104. The magneticfield receiving coil 104 connects to the flat electrodes 102 a and 102 bin series and has an auxiliary radiating function to couple the feedercircuit 21 and the radiating plate 32 (see FIG. 2).

The feeder circuit 21 including the inductance elements L1 and L2according to the sixth preferred embodiment has the same equivalentcircuit as that of the feeder circuit 21 illustrated in FIG. 1. Theinductance elements L1 and L2 magnetically couple to each other inopposite phases and resonate with frequencies processed by the radiofrequency IC chip 10, and also electromagnetically couple to theradiating plate 32. Also, the feeder circuit 21 realizes matchingbetween the impedance of the radio frequency IC chip 10 (normally about50Ω) and the impedance of the radiating plate 32 (spatial impedance ofabout 377Ω). Thus, the operation and effect of the sixth preferredembodiment are the same as those of the first preferred embodiment.

Seventh Preferred Embodiment FIG. 13

A radio frequency IC device according to a seventh preferred embodimentincludes the feeder circuit substrate 20 illustrated in FIG. 13. Theother components, that is, the radio frequency IC chip 10 and theradiating substrate 30, are preferably the same as those of the firstpreferred embodiment.

In the feeder circuit substrate 20, wiring electrodes 111 a and 111 b,which are adjacent to each other and are spirally connected, define theinductance elements L1 and L2. The inductance elements L1 and L2 haveinductance values different from each other and magnetically couple toeach other in opposite phases.

Furthermore, flat electrodes 112 a and 112 b are placed immediatelybelow the inductance elements L1 and L2, and spirally connected wiringelectrodes 113 define a magnetic field receiving coil 114. The magneticfield receiving coil 114 connects to the flat electrodes 112 a and 112 bin series and has an auxiliary radiating function to couple the feedercircuit 21 and the radiating plate 32 (see FIG. 2).

The feeder circuit 21 including the inductance elements L1 and L2according to the seventh preferred embodiment has the same equivalentcircuit as that of the feeder circuit 21 illustrated in FIG. 1. Theinductance elements L1 and L2 magnetically couple to each other inopposite phases and resonate with frequencies processed by the radiofrequency IC chip 10, and also electromagnetically couple to theradiating plate 32. Also, the feeder circuit 21 realizes matchingbetween the impedance of the radio frequency IC chip 10 (normally about50Ω) and the impedance of the radiating plate 32 (spatial impedance ofabout 377Ω). Thus, the operation and effect of the seventh preferredembodiment are the same as those of the first preferred embodiment.

Particularly, in the seventh preferred embodiment, the two wiringelectrodes 111 a and 111 b adjacent to each other on the same plane formthe inductance elements L1 and L2. By changing the length of the wiringelectrodes 111 a and 111 b or the gap therebetween, a wideband resonancecharacteristic can be obtained.

Eighth Preferred Embodiment See FIGS. 14 to 17

A radio frequency IC device according to an eighth preferred embodimentincludes the feeder circuit substrate 20 illustrated in FIG. 14. Thisfeeder circuit 21 preferably is basically the same as that of the fifthpreferred embodiment (see FIG. 11). That is, feeder terminal electrodes122 a and 122 b and mount electrodes 123 a and 123 b are disposed on asheet 121 a, and wiring electrodes 125 a and 125 b are disposed on eachof sheets 121 b to 121 g. Furthermore, flat electrodes 128 a and 128 bare placed on a sheet 121 h.

The inductance elements L1 and L2 are formed by spirally connecting thewiring electrodes 125 a and 125 b, which are integrated in a wiringelectrode 1 125 on the sheet 121 b. An end portion 125 a′ of the wiringelectrode 125 a on the sheet 121 g connects to the feeder terminalelectrode 122 a, and an end portion 125 b′ of the wiring electrode 125 bon the sheet 121 g connects to the feeder terminal electrode 122 b.

The feeder circuit 21 having the above-described configuration includingthe inductance elements L1 and L2 has the equivalent circuit illustratedin FIG. 15. The inductance elements L1 and L2, which connect to theradio frequency IC chip 10 in series, magnetically couple to each otherin opposite phases and resonate with frequencies processed by the radiofrequency IC chip 10, and also electromagnetically couple to a radiatingplate 52 (or the radiating plate 32). Also, the feeder circuit 21realizes matching between the impedance of the radio frequency IC chip10 (normally about 50Ω) and the impedance of the radiating plate 32 or52 (spatial impedance of about 377Ω).

Thus, the operation and effect of the eighth preferred embodiment arethe same as those of the first preferred embodiment. Particularly,variations in coupling between the feeder circuit 21 and the radiatingplate 32 or 52 can be prevented by providing the flat electrodes 128 aand 128 b on the rear surface of the feeder circuit substrate 20. Theflat electrodes 128 a and 128 b are not always necessary.

Furthermore, in the eighth preferred embodiment, the positions where theend portions of the inductance elements L1 and L2 connect to the feederterminal electrodes 122 a and 122 b can be changed and the end portions125 a′ and 125 b′ can be electrically open so as to constitute anauxiliary matching circuit.

For example, as illustrated in FIG. 16, leading electrodes 125 a″ and125 b″ are provided to the wiring electrodes 125 a and 125 b on thesheet 121 e, and the leading electrodes 125 a″ and 125 b″ are connectedto the feeder terminal electrodes 122 a and 122 b. Then, the endportions 125 a′ and 125 b′ of the wiring electrodes 125 a and 125 b onthe sheet 121 g are electrically open, and an auxiliary matching circuit129 is defined by the wiring electrodes 125 a and 125 b on the sheets121 f and 121 g. The leading electrodes 125 a″ and 125 b″ connected tothe feeder terminal electrodes 122 a and 122 b may be provided to any ofthe wiring electrodes 125 a and 125 b placed on the sheets 121 c to 121f. The equivalent circuit thereof is illustrated in FIG. 17. By formingthe auxiliary matching circuit 129, a matching state can be finelyadjusted.

Ninth Preferred Embodiment FIGS. 18 to 20

A radio frequency IC device according to a ninth preferred embodimentincludes the feeder circuit substrate 20 that is provided with the radiofrequency IC chip 10 and that is bonded onto the radiating substrate 30as illustrated in FIG. 18, and is bonded to a recessed portion 141 on afront or rear surface of a metallic can 140 as illustrated in FIG. 19.The metallic can 140 is preferably made of a metallic material, such assteel or aluminum, for example. The feeder circuit substrate 20 is thesame as that in the first preferred embodiment and includes the feedercircuit 21 illustrated in FIG. 4. The radiating substrate 30 includesthe loop-shaped radiating plate 32 having the end portions 32 a and 32 bplaced on the film substrate 31 illustrated in FIGS. 2A and 2B. Notethat the film substrate 31 and the radiating plate 32 illustrated inFIGS. 2A and 2B are rectangular, whereas those in the ninth preferredembodiment are preferably oval-shaped as illustrated in FIG. 18.

As illustrated in FIG. 20, the radiating substrate 30 provided with theradio frequency IC chip 10 and the feeder circuit substrate 20 is bondedto the bottom of the recessed portion 141 through a mat 142 of whichboth surfaces are applied with an adhesive. The depth H1 of the recessedportion 141 is preferably about 5 mm, the height H2 from the bottom ofthe recessed portion 141 to the radiating plate 32 is preferably about 2mm to about 3 mm, for example. Preferably, the radio frequency IC chip10 should not protrude from the recessed portion 141.

The operation and effect of the ninth preferred embodiment are the sameas those of the first preferred embodiment. Incidentally, a magneticfield φ (see FIG. 20) is generated around the loop-shaped radiatingplate 32 during transmission/reception of signals. This magnetic fielddoes not pass through metal. Thus, if metal and the loop-shapedradiating plate 32 are arranged parallel or substantially parallel andare close to each other, a magnetic field generated by the radiatingplate 32 is blocked by the metal and is not sufficiently radiated to theoutside, which impairs the function of the radio frequency IC device. Inthe ninth preferred embodiment, the radiating plate 32 is spaced apartfrom the bottom of the recessed portion 141 of the metallic can 140 byabout several mm through the mat 142 or the like, so that the magneticfield φ can be radiated from the radiating plate 32 and that the radiofrequency IC device can function.

Alternatively, the radiating substrate 30 provided with the feedercircuit substrate 20 may be embedded in the mat 142. Furthermore, theradiating substrate 30 may have a thickness comparable to that of themat 142, and the feeder circuit substrate 20 may be embedded in arecessed portion defined in the radiating substrate 30. Alternatively,the radio frequency IC chip 10 may be sandwiched by the feeder circuitsubstrate 20 and the radiating substrate 30. With this configuration,the radio frequency IC chip 10 and the feeder circuit substrate 20 canbe protected against a drop or impact, and the mechanical strength ofthe radio frequency IC device can be enhanced. The radio frequency ICdevice is bonded to the metallic can 140 in this preferred embodiment.Other than the metallic can, any article made of a metallic material maybe used, e.g., a metallic case or a ground electrode on the circuitsubstrate.

Tenth Preferred Embodiment FIGS. 21 to 23B

The radio frequency IC device according to each of the above-describedpreferred embodiments preferably includes a feeder circuit substrateincluding a feeder circuit having a resonance circuit and/or a matchingcircuit. However, the feeder circuit substrate is unnecessary in theradio frequency IC device. A feeder circuit having a resonance circuitand/or a matching circuit including at least two inductance elements maybe provided on a rear surface (front surface) where input/outputterminal electrodes of a radio frequency IC chip are placed.Hereinafter, such a radio frequency IC device is described as tenth andeleventh preferred embodiments.

In a radio frequency IC device according to the tenth preferredembodiment, a feeder circuit 150 illustrated in an equivalent circuitdiagram in FIG. 21 is provided on a rear surface of the radio frequencyIC chip 10. The feeder circuit 150 includes two inductance elements L1and L2, arranged in spiral patterns wound in opposite directions,connected in series. Feeder terminal electrodes 151 a and 151 b providedat one ends of the respective inductance elements L1 and L2 are inelectrical conduction with the input/output terminal electrodes of theradio frequency IC chip 10. The inductance elements L1 and L2magnetically couple to each other in opposite phases, define a resonancecircuit together with stray capacitance between the coils, the resonancecircuit resonating at frequencies processed by the radio frequency ICchip 10, and electromagnetically couple to a radiating plate (e.g., theend portions 32 a and 32 b of the radiating plate 32 illustrated inFIGS. 2A and 2B). Therefore, the operation and effect of the tenthpreferred embodiment are the same as those of the first preferredembodiment.

In the feeder circuit 150, a midpoint between the inductance elements L1and L2 serves as a virtual ground. An impedance value of the feedercircuit 150 is designed to be a complex conjugate with respect to animpedance value of the radio frequency IC chip 10. The inductanceelements L1 and L2 are formed in a laminated state as illustrated inFIGS. 22A to 22G, and thus the inductance values thereof vary inaccordance with a distance to the radiating plate. Then, an insulatinglayer 159 is placed on the rear surface of the radio frequency IC chip10 so as to fix the distance to the radiating plate and to protect theinductance elements L1 and L2.

The feeder circuit 150 is fabricated in a process illustrated in FIGS.22A to 22G. First, as illustrated in FIG. 22A, an insulating layer 152is formed on the rear surface of the radio frequency IC chip 10 except aportion of the input/output terminal electrodes. Then, as illustrated inFIG. 22B, an electrode layer 153 is formed on the insulating layer 152by, for example, plating or the like, and etching is performed in apredetermined shape (see FIG. 22C). This state is illustrated in FIG.23A.

Then, as illustrated in FIG. 22D, an insulating layer 154 is formed onthe electrode layer 153. Furthermore, as illustrated in FIG. 22E, anelectrode layer 155 is formed on the insulating layer 154 by plating orthe like, and etching is performed in a predetermined shape (see FIG.22F). This state is illustrated in FIG. 23B. Furthermore, as illustratedin FIG. 22G, an insulating layer 159 is formed on the electrode layer155.

Eleventh Preferred Embodiment FIGS. 24 to 26C

In a radio frequency IC device according to the eleventh preferredembodiment, the feeder circuit 150 illustrated in an equivalent circuitdiagram in FIG. 24 is provided on the rear surface of the radiofrequency IC chip 10. This feeder circuit 150 is defined by inserting acapacitor C between the inductance elements L1 and L2 in the equivalentcircuit (see FIG. 21) according to the tenth preferred embodiment, todefine a series resonance circuit. The operation and effect of theeleventh preferred embodiment is the same as those of the tenthpreferred embodiment.

The feeder circuit 150 illustrated in FIG. 24 is fabricated in a processillustrated in FIGS. 25A to 25G. First, as illustrated in FIG. 25A, aninsulating layer 156 is formed on the rear surface of the radiofrequency IC chip 10 except a portion of the input/output terminalelectrodes. Then, as illustrated in FIG. 25B, an electrode layer 157 isformed on the insulating layer 156 by, for example, plating or the like,and etching is performed in a predetermined shape (see FIG. 25C). Thisstate is illustrated in FIG. 26A. An electrode 157 a formed at a centerportion serves as one capacitor electrode.

Then, as illustrated in FIG. 25D, an insulating layer 152 is formed onthe electrode layer 157. Furthermore, as illustrated in FIG. 25E, anelectrode layer 153 is formed on the insulating layer 152 by plating orthe like, and etching is performed in a predetermined shape (see FIG.25F). This state is illustrated in FIG. 26B. At this time, electrodes153 a and 153 b facing the capacitor electrode 157 a are formed.

Furthermore, as illustrated in FIG. 25G, an insulating layer 154 isformed on the electrode layer 153. Then, as illustrated in FIGS. 22E,22F, and 22G, the electrode layer 155 and the insulating layer 159 areformed. The state where the electrode layer 155 is formed is illustratedin FIG. 123C.

Twelfth to Fifteenth Preferred Embodiments See FIGS. 27A to 31D

A radio frequency IC device according to a twelfth preferred embodimentincludes a feeder circuit 200 including inductance elements L1 and L2,arranged in spiral patterns wound in opposite directions, connected inseries, as illustrated in an equivalent circuit diagram in FIG. 27A.Both ends of a radiating plate 212 constituted by a loop-shapedelectrode having an inductance component L10 are in electricalconduction with both ends of the inductance elements L1 and L2. Also,feeder terminal electrodes 201 a and 201 b that connect to theinput/output terminal electrodes of the radio frequency IC chip 10 areprovided at both ends of the feeder circuit 200.

A radio frequency IC device according to a thirteenth preferredembodiment includes a capacitor C that connect in parallel to theinductance elements L1 and L2, as illustrated in an equivalent circuitdiagram in FIG. 27B. Other than that, the configuration is preferablythe same as that in the twelfth preferred embodiment.

A radio frequency IC device according to a fourteenth preferredembodiment includes the feeder circuit 200 including the inductanceelements L1 and L2, arranged in spiral patterns wound in oppositedirections, connected in series, as illustrated in an equivalent circuitdiagram in FIG. 28A. Spiral inductance components L11 and L12 providedat both ends of the radiating plate 212 constituted by the loop-shapedelectrode having the inductance component L10 are electromagneticallycoupled to the inductance elements L1 and L2. Also, the feeder terminalelectrodes 201 a and 201 b that connect to the input/output terminalelectrodes of the radio frequency IC chip 10 are provided at both endsof the feeder circuit 200.

A radio frequency IC device according to a fifteenth preferredembodiment includes a capacitor C that connect in parallel to theinductance elements L1 and L2, as illustrated in an equivalent circuitdiagram in FIG. 125B. Other than that, the configuration is preferablythe same as that in the fourteenth preferred embodiment.

In the fourteenth and fifteenth preferred embodiments, spiral receivingelectrodes (the inductance components L11 and L12) are arranged at theboth ends of the radiating plate 212 such that the receiving electrodesoppose the inductance elements L1 and L2 of the feeder circuit 200. Withthis arrangement, the direction of a magnetic field generated by theinductance component L10 of the radiating plate 212 is the same as thatof a magnetic field generated by the feeder circuit 200, so that thedegree of coupling between the feeder circuit 200 and the radiatingplate 212 is increased.

Also, since the receiving electrodes (the inductance components L11 andL12) provided at the both ends of the radiating plate 212 have spiralpatterns wound in opposite directions, energy passing efficiencyincreases. Furthermore, each of the inductance elements and each of thespiral ends of the radiating plate formed to couple to each other (L1and L11, L2 and L12) are wound in the same directions, respectively,when the feeder circuit 200 is viewed in a perspective plan view. Thedirections of magnetic fields generated in the respective two spiralelectrodes (L1 and L11, L2 and L12) placed to oppose each other in aperspective plan view are the same, so that the strength of magneticcoupling between the feeder circuit 200 and the radiating plate 212increases.

Furthermore, the inductance value (L10) of the loop-shaped electrode ofthe radiating plate 212 is preferably set to be larger than theinductance value of the inductance elements L1 and L2 of the feedercircuit 200. Signals from the feeder circuit 200 can betransmitted/received through a magnetic field generated by the radiatingplate 212, so that occurrence of communication failure with areader/writer can be minimized.

Now, a specific configuration of the twelfth to fifteenth preferredembodiments illustrated in the equivalent circuit diagrams is described.As illustrated in FIGS. 29A to 29D, those radio frequency IC devicesinclude the radio frequency IC chip 10, a feeder circuit substrate 220,and a radiating substrate 210 including the radiating plate 212 (seeFIGS. 31A to 31D). The feeder terminal electrodes 201 a and 201 b areprovided on a front surface of the feeder circuit substrate 220 (seeFIG. 29B), and flat electrodes 202 a and 202 b are provided on a rearsurface thereof (see FIG. 29C). The operation and effect of the flatelectrodes 202 a and 202 b are as described in the second preferredembodiment (see FIG. 5). Alternatively, the flat electrodes 202 a and202 b may be omitted as illustrated in FIG. 29D.

The feeder circuit 200 illustrated in FIG. 30 is provided inside thefeeder circuit substrate 220. The feeder circuit substrate 220 is formedby, for example, laminating, crimping, and firing dielectric or magneticceramic sheets. A sheet 231 a in the top layer is provided with thefeeder terminal electrodes 201 a and 201 b and mount electrodes 201 cand 201 d. A sheet 231 b in the second layer is provided with connectingelectrodes 203 a and 203 b. Each of sheets 231 c to 231 g in the thirdto seventh layers is provided with wiring electrodes 204 a and 204 bdefining the inductance elements L1 and L2.

By laminating the sheets 231 a to 231 g, the wiring electrodes 204 a arespirally connected by via-hole conductors 205 a to form the inductanceelement L1, while the wiring electrodes 204 b are spirally connected byvia-hole conductors 205 b so as to form the inductance element L2.Individual ends of the inductance elements L1 and l2 (wiring electrodes204 a and 204 b) are mutually connected in a conductive manner on thesheet 231 c, and the other ends thereof are connected to the feederterminal electrodes 201 a and 201 b through the connecting electrodes203 a and 203 b and via-hole conductors 206 a and 206 b.

The operation and effect of the feeder circuit 200 having theabove-described configuration are the same as those of the first andsecond preferred embodiments. Particularly, in the feeder circuit 200illustrated in FIG. 30, individual ends of the two inductance elementsL1 and L2 are mutually connected in a conducting manner near the toplayer in the laminate and the other ends are connected to the radiofrequency IC chip 10. Also, the inductance elements L1 and L2 areconnected in a conducting manner near the top layer in the laminateapart from the radiating plate 212 and are wound in directions oppositeto each other near a lower layer of the laminate where electromagneticcoupling with the radiating plate 212 is achieved. Accordingly, energypassing efficiency increases.

As illustrated in FIGS. 31A to 31D, the radiating substrate 210 includesthe spiral radiating plate 212 that has one end 212 a and another end212 b and that is provided on a front surface of a flexible resin film211 and also includes an electrode 213 adjacent to the one end 212 a.The electrode 213 is in electrical conduction with the other end 212 bof the radiating plate 212 via a connecting electrode 214 placed on arear surface of the substrate 211 and a via-hole conductor. Also, thefeeder circuit substrate 220 on which the radio frequency IC chip 10 ismounted is coupled to the one end 212 a of the radiating plate 212 andone end 213 a of the electrode 213.

The one end 212 a of the radiating plate 212 and the one end 213 a ofthe electrode 213 may be flat as illustrated in FIG. 31B or may bespiral as illustrated in FIG. 31C. When the one end 212 a of theradiating plate 212 and the one end 213 a of the electrode 213 arespiral, which corresponds to the fourteenth and fifteenth preferredembodiments.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing the scope andspirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1. A radio frequency IC device comprising: a radio frequency IC; afeeder circuit that is coupled to the radio frequency IC, the feedercircuit is provided on a principal surface provided with input/outputterminal electrodes of the radio frequency IC, and includes a resonancecircuit including at least two inductance elements and/or a matchingcircuit including at least two inductance elements; and a radiatingplate arranged to radiate a transmission signal supplied from the feedercircuit and/or supply a received signal to the feeder circuit; whereinthe feeder circuit is bonded to or placed near the radiating plate; andthe at least two inductance elements include spiral patterns wound inopposite directions.
 2. A radio frequency IC device comprising: a radiofrequency IC chip; a feeder circuit substrate electrically connected tothe radio frequency IC chip and provided with a feeder circuit includinga resonance circuit including at least two inductance elements and/or amatching circuit including at least two inductance elements; and aradiating plate arranged to radiate a transmission signal supplied fromthe feeder circuit and/or supply a received signal to the feedercircuit; wherein the feeder circuit substrate is bonded to or placednear the radiating plate; and the at least two inductance elementsinclude spiral patterns wound in opposite directions.
 3. The radiofrequency IC device according to claim 2, wherein a resonance frequencyof the transmission signal and/or the received signal substantiallycorresponds to a resonance frequency of the resonance circuit.
 4. Theradio frequency IC device according to claim 2, wherein the at least twoinductance elements are in different positions when the feeder circuitsubstrate is viewed in a perspective plan view.
 5. The radio frequencyIC device according to claim 2, wherein each of the at least twoinductance elements includes two wiring electrodes adjacent to eachother on the same plane.
 6. The radio frequency IC device according toclaim 2, wherein the feeder circuit substrate includes a laminate andwherein an inside or a surface of a bottom layer of the laminate isprovided with flat electrodes, a size of the laminate being about thesame as or smaller than that of an outer shape of the at least twoinductance elements when the feeder circuit substrate is viewed in aperspective plan view.
 7. The radio frequency IC device according toclaim 1, wherein individual ends of the at least two inductance elementsare mutually connected in an electrically conductive manner near a toplayer in a laminate and other ends of the at least two inductanceelements are coupled to the radio frequency IC.
 8. The radio frequencyIC device according to claim 2, wherein the feeder circuit substrateincludes a magnetic substance; and the at least two inductance elementsare placed in the magnetic substance.
 9. The radio frequency IC deviceaccording to claim 2, wherein the radiating plate is defined by aloop-shaped electrode having one end and another end and each of the oneend and another end couples to one of the at least two inductanceelements.
 10. The radio frequency IC device according to claim 9,wherein the inductance elements and spiral end portions of the radiatingplate that are arranged to couple to each other are wound in the samedirections when the feeder circuit is viewed in a perspective plan view.11. The radio frequency IC device according to claim 9, wherein aninductance value of the loop-shaped electrode is larger than aninductance value of the inductance elements of the feeder circuit. 12.The radio frequency IC device according to claim 9, wherein a magneticsubstance is placed inside or on a surface of a loop of the loop-shapedelectrode.
 13. The radio frequency IC device according to claim 2,wherein the at least two inductance elements connect to the radiofrequency IC chip in series.
 14. The radio frequency IC device accordingto claim 2, wherein the at least two inductance elements connect to theradio frequency IC chip in parallel.
 15. The radio frequency IC deviceaccording to claim 2, wherein inductance values of the at least twoinductance elements are substantially the same.
 16. The radio frequencyIC device according to claim 2, wherein a plurality of mount electrodesarranged to mount the radio frequency IC chip are placed on a principalsurface of the feeder circuit substrate; and at least two of theplurality of mount electrodes are electrically connected through thefeeder circuit.
 17. The radio frequency IC device according to claim 16,wherein the at least two mount electrodes are balanced input/outputterminal electrodes.
 18. The radio frequency IC device according toclaim 2, wherein the feeder circuit includes an auxiliary matchingcircuit having one end electrically connected to a predeterminedposition of the feeder circuit and another end that is electricallyopen.
 19. The radio frequency IC device according to claim 2, wherein aportion of the at least two inductance elements is exposed on a sidesurface of the feeder circuit substrate; and the exposed portion alsodefines as a radiating plate.
 20. The radio frequency IC deviceaccording to claim 2, wherein the feeder circuit substrate is amultilayer substrate made of ceramic or resin.
 21. The radio frequencyIC device according to claim 2, wherein the feeder circuit substrate isa flexible substrate.